1. Field of the Invention
This invention relates to string-type trimmers, and more particularly to heavy-duty, wheel-mounted powered trimmers for severe service such as cemetery maintenance.
2. Background Art
In recent years, powered string trimmers have gained wide acceptance for home and commercial grass and weed control, particularly for edging and trimming along or around walks, curbs, fences, and other obstacles. Most of the currently available string trimmers are hand held units powered by small electric motors or two-cycle gasoline engines. These units have met with considerable success, but have certain drawbacks when used for severe service such as highway or long fence maintenance or for cemetery maintenance. In these uses, the many hours of continuous service present both equipment durability and operator fatigue problems as well as safety problems.
U.S. Pat. No. 4,703,613 to Raymond describes a trimmer with a cutting head that can be tilted and positioned adjacent either wheel. The mechanism for allowing this head movement involves moving both wheels simultaneously relative to the frame by an operator applying torque through the handle.
U.S. Pat. No. 4,077,191 describes a trimmer with a cutter head having a variable position relative to a support mechanism.
U.S. Pat. No. 5,313,770 to Smothers describes a trimmer having a "jam-proof" drive mechanism.
None of the above-noted devices includes a pair of wheels each being independently height adjustable relative to a support frame. Also, none of them suggest use of a centrifugal clutch in the drive train to cause trimmer head rotation only upon reaching a predetermined engine speed. Finally, none of them suggests an adjustable handle angle relative to a frame.